1. Field of the Invention
The present invention relates to a steering column including a jacket tube for receiving at least a section of a steering gear shaft, a bracket member for securing the steering column to a body of a motor vehicle, and a locking device having a closed position in which the jacket tube is fixedly secured to the bracket member, and an open position in which the jacket tube is displaceable, within predetermined limits, relative to the bracket member.
2. Description of the Prior Art
Different embodiments of a steering column, which is described above, are well known. Usually, in the open position of the locking device, both the length of the steering column and its inclination or height can be adjusted. For fixing the jacket tube in the closed position of the locking device, crossing each other, packs of lamellas are provided one of which is secured to the bracket tube and another of which is secured on the bracket member. The lamella packs are pierced by a locking bolt which is tensioned by a pull device. A steering column of the type described above is disclosed, e.g., in European Publication EP 0 802 104 B1. For effecting the necessary adjustment, crossing each other elongate openings are provided in the lamella packs, in the jacket tube, and in the bracket member, with the locking bolt extending through the elongate openings. Locking devices with lamellas or lamella-like elements are discloses, e.g., in European Publications EP 121 506 B1; EP-0 440 698 B1 and U.S. Pat. No. 5,606,891. The drawback of the steering columns, which including locking devices with lamellas, consists in that for obtaining a high retaining force in the closed position of the locking device, a relatively large number of lamellas is required. This results in that for adjusting the steering column in the open position of the locking device, a relatively large friction force has to be overcome.
European Publication EP-0 836 981 B1 discloses an adjustable steering column the locking device of which has toothed members the teeth of which engage each other in the closed position of the locking device. With this locking device, the adjustment of the steering column in the open position of the locking device can be effected rather easily. However, with the locking device of this type, there can be cases when the tips of opposite teeth are located directly opposite each other, and upon closing of the device, it cannot be properly closed. In case of a crash, an uncontrolled displacement of the steering column can take place. Furthermore, in case the tips of the teeth are located directly opposite each other, the device cannot be closed at all or is closed incompletely, and/or requires application of a substantial force for closing.
Accordingly, an object of the present invention is a steering column of the type discussed above and that can be easily adjusted in the open position of the locking device.
Another object of the present invention is a steering column of the type described above and the locking device of which can be easily closed in any of adjustment positions of the steering column.